David A. Johnston

, which measures ultraviolet radiation as an indicator of the sulfur dioxide content of gases ejected from Mount St. Helens. Photographed on April 4, 1980.|alt=Black and white photograph; a man squints into the telescopic eyepiece of a large mechanical device. Johnston was born at the University of Chicago Hospital on December 18, 1949, to Thomas and Alice Johnston. They originally lived in Hometown, Illinois, but moved to Oak Lawn shortly after Johnston's birth, where he grew to adulthood. Johnston spent the summer after college in the San Juan volcanic field of Colorado working with volcanologist Pete Lipman in his study of two extinct calderas. Johnston's reconstruction of the eruptive history of the extinct volcanoes prepared him to study active volcanoes. During the summers of 1978 and 1979, Johnston led studies of the ash-flow sheet emplaced in the 1912 eruption of Mount Katmai in the Valley of Ten Thousand Smokes. Fellow volcanologist Wes Hildreth said of Johnston, "I think Dave's dearest hope was that systematic monitoring of fumarolic emissions might permit detection of changes characteristically precursory to eruptions ... Dave wanted to formulate a general model for the behavior of magmatic volatiles prior to explosive outbursts and to develop a corollary rationale for the evaluation of hazards." Johnston was the first geologist on the volcano, and soon became a leader within the USGS team, taking charge of monitoring of volcanic gas emissions. == Eruption of Mount St. Helens ==

Precursor activity Since its last eruptive activity in 1857, Mount St. Helens had been largely dormant. Seismographs were not installed until 1972. This period of 123 years of inactivity ended in early 1980. On March 15, a cluster of tiny earthquakes rocked the area around the mountain. For six days, more than 100 earthquakes clustered around Mount St. Helens, an indication that magma was moving. There was initially some doubt as to whether the earthquakes were precursors to an eruption. By March 20, a magnitude 4.2 earthquake shook the wilderness around the volcano. The next day, seismologists installed three seismic recorder stations. By March 24, volcanologists at the USGS—including Johnston—became more confident that the seismic activity was a sign of an impending eruption. After March 25, seismic activity drastically increased. By March 26, more than seven earthquakes over magnitude 4.0 had been recorded, and the next day, hazard warnings were publicly issued. Spectators congregated in the vicinity of the mountain, hoping for a chance to see its eruptions. They were joined by reporters in helicopters, as well as mountain climbers. Rising magma under Mount St. Helens had veered off to the north flank, creating a growing bulge on the surface. and established the Coldwater I and II observation posts to use laser ranging to measure how the distances to these reflectors changed over time as the domes deformed. Coldwater II, where Johnston died, was located just north of the mountain. To the astonishment of the USGS geologists, the bulge was growing at a rate of 5 to 8 feet (1.5 to 2.4 meters) per day. .|alt=A man climbing a steep cliff face dwarfed by massive boulders around him. Tiltmeters installed on the volcano's north side displayed a northwest trending tilt for that side of the mountain, and a southwest trending tilt was observed on the south side. Worried that the amount of pressure on the magma underground was increasing, scientists analyzed gases by the crater, and found high traces of sulfur dioxide. After this discovery, they began to regularly check the fumarolic activity and monitor the volcano for dramatic changes, but none were observed. Disheartened, they instead opted to study the growing bulge and the threat an avalanche could have for humans relatively near the volcano. An evaluation of the threat was carried out, concluding that a landslide or avalanche in the Toutle River could spawn lahars, or mudflows, downstream. It was the largest subaerial (on land) landslide in Earth's recorded history. With the loss of the confining pressure of the overlying rock, Mount St. Helens began to rapidly emit steam and other volcanic gases. A few seconds later, it erupted laterally, sending swift pyroclastic flows down its flanks at near supersonic speeds. These flows were later joined by lahars. Before being struck by a series of flows that, at their fastest, would have taken less than a minute to reach his position , Johnston attempted to radio his USGS co-workers with the message: "Vancouver! Vancouver! This is it! Vancouver, is the transmitter on?" The cloud of the eruption blocked the transmission of his message to Vancouver; his final words were recorded by an amateur radio operator. Seconds later, the signal from the radio went silent, and all contact with the geologist was lost. The extent, speed and direction of the avalanche and pyroclastic flows that overwhelmed Johnston, Martin, and others were later described in detail in a paper titled 'Chronology and Character of the May 18, 1980 Explosive Eruptions of Mount St. Helens', published in 1984 in a collection published by the National Research Council's Geophysics Study Committee. In this paper, the authors examined photographs and satellite images of the eruption to construct a chronology and description of the first few minutes. Included in the paper is figure 10.3, a series of timed photographs taken from Mount Adams, east of Mount St. Helens. These six photographs, taken sideways on to the lateral blast, vividly show the extent and size of the avalanche and flows as they reached northwards over and beyond Johnston's position. Figure 10.7 from the same paper is an overhead diagram showing the position of the pyroclastic surge front at half-minute intervals, with the positions of Johnston (Coldwater II) and Martin included. but some of those who survived the eruption declared that the landslide and pyroclastic flows were silent as they raced down the mountain. Kran Kilpatrick, an employee of the United States Forest Service, recalled, "There was no sound to it, not a sound. It was like a silent movie and we were all in it." The reason for this discrepancy is a "quiet zone", created as a result of the motion and temperature of air and, to a lesser extent, upon local topography. Johnston had been among the first volcanologists at the volcano when eruptive signs appeared, and shortly after was named the head of volcanic gas monitoring. He and several other volcanologists prevented people from being near the volcano during the few months of pre-eruptive activity, and successfully fought pressure to re-open the area. The evening before the eruption he was scheduled to be relieved by USGS geologist Don Swanson, but something came up, and Swanson asked Johnston to take his place. Johnston agreed. That Saturday, the day before the eruption took place, Johnston ascended the mountain and went on a patrol of the volcano with geologist Carolyn Driedger. Tremors shook the mountain. Driedger was supposed to camp on one of the ridges overlooking the volcano that night, but Johnston told her to head home and said that he would stay on the volcano alone. While at Coldwater II, Johnston was to observe the volcano for any further signs of an eruption. Just prior to his departure, at 7 p.m. on the evening of May 17, 13½ hours before the eruption, Glicken took the famous photograph of Johnston sitting by the observation-post trailer with a notebook on his lap, smiling. the volcano erupted. Immediately, rescue workers were dispatched to the area. The official USGS pilot, Lon Stickney, who had been flying the scientists to the mountain, conducted the first rescue attempt. He flew his helicopter over the scarred remains of trees, valleys, and the Coldwater II observation post ridge, where he saw bare rock and uprooted trees. Because he saw no sign of Johnston's trailer, Stickney began to panic, becoming "emotionally distraught". Frantic and guilt-stricken, Harry Glicken convinced three separate helicopter pilots to take him up on flights over the devastated area in a rescue attempt, but the eruption had so changed the landscape that they were unable to locate any sign of the Coldwater II observation post. In 1993, while building a extension of Washington State Route 504 (also called "Spirit Lake Memorial Highway") to lead to the Johnston Ridge Observatory, construction workers discovered pieces of Johnston's trailer. His body, however, has never been found. Consequences and response The public was shocked by the extent of the eruption, which had lowered the elevation of the summit by , destroyed of woodland, and spread ash into other states and Canada. The lateral blast that killed Johnston started at a speed of and accelerated to . == Legacy ==

Scientific Johnston was commemorated both by his fellow scientists and by the government. Known for his diligent and particular nature, he was called "an exemplary scientist" by a USGS dedication paper, which also described him as "unaffectedly genuine, with an infectious curiosity and enthusiasm". Following the eruption, Harry Glicken and other geologists at the USGS dedicated their work to Johnston. Because Johnston was believed to be safe at the Coldwater II observation post, the fact that he died shocked his friends and co-workers alike. However, most of his colleagues and family asserted that Johnston died "doing what he wanted to do." Geologists can now identify characteristic patterns in seismic waves that indicate particular magmatic activity. In particular, volcanologists have used deep, long-period earthquakes that indicate that magma is rising through the crust. They can also use carbon dioxide emission as a proxy for magma supply rate. Measurements of surface deformation due to magmatic intrusions, like those that were conducted by Johnston and the other USGS scientists at the Coldwater I and II outposts, have advanced in scale and precision. Ground deformation monitoring networks around volcanoes now consist of InSAR (interferometry), surveys of networks of GPS monuments, microgravity surveys in which scientists measure the change in gravitational potential or acceleration because of the intruding magma and resulting deformation, strain meters, and tiltmeters. Though there is still work to be done, this combination of approaches has greatly improved scientists' abilities to forecast volcanic eruptions. Glicken was being mentored by Johnston, who relieved Glicken of his watch at the Coldwater II observation post 13 hours before Mount St. Helens erupted. Commemoration Early acts of commemoration included two trees that were planted in Tel Aviv, Israel, On the second anniversary of the eruption, the USGS office in Vancouver (which had been permanently established following the 1980 eruption) was renamed the David A. Johnston Cascades Volcano Observatory (CVO) in his memory. This volcano observatory is the one most responsible for monitoring Mount St. Helens, and helped to predict all of the volcano's eruptions between 1980 and 1985. In a 2005 open day, the lobby area of the CVO included a display and painting commemorating Johnston. Johnston's connections with the University of Washington (where he had carried out his masters and doctoral research) are remembered by a memorial fund that established an endowed graduate-level fellowship within what is now the department of Earth and Space Sciences. By the time of the first anniversary of his death, the fund had exceeded $30,000. Known as the 'David A. Johnston Memorial Fellowship for Research Excellence', a number of awards of this fellowship have been made over the years since it was launched. Following the eruption, the area where the Coldwater II observation post had been was sectioned off. Eventually, an observatory was built in the area in Johnston's name, and opened in 1997. Located just over from the north flank of Mount St. Helens, the Johnston Ridge Observatory (JRO) allows the public to admire the open crater, new activity, and the creations of the 1980 eruption, including an extensive basalt field. Part of the Mount St. Helens National Volcanic Monument, the JRO was constructed for , equipped with monitoring equipment. Visited by thousands of tourists annually, it also includes tours, a theater, and an exhibit hall. There are several public memorials where Johnston's name is inscribed in a list of those known to have died in the eruption. These memorials include a large curved granite monument at an outside viewing area at the Johnston Ridge Observatory, which opened in 1997, and a plaque at the Hoffstadt Bluffs Visitor Center, which was unveiled in a memorial grove in May 2000. Depictions There have been several tellings of Johnston's story in documentaries, films and docudramas about the eruption. The most comprehensive depiction is the 2019 book A Hero on Mount St. Helens: The Life and Legacy of David A. Johnston, written by Melanie Holmes (University of Illinois Press); written at the behest of his family. In the 1981 HBO television film St. Helens, actor David Huffman starred as David Jackson, a fictional character supposedly based on Johnston, but with almost no representation of his actions in 1980. Johnston's parents objected to the production of the film, arguing that it possessed not "an ounce of David in it" and portrayed "him as a daredevil rather than a careful scientist". Prior to the film's premiere on May 18, 1981, the first anniversary of the eruption, 36 scientists who knew Johnston signed a letter of protest. They wrote that, "Dave's life was too meritorious to require fictional embellishments," and that, "Dave was a superbly conscientious and creative scientist."   Several documentaries and docudramas have covered the history of the eruption, including archive footage and dramatisations of Johnston's story. These include Up From the Ashes (1990) by KOMO-TV, an episode of the 2005 second series of Seconds From Disaster broadcast by the National Geographic Channel, an episode of the 2006 series Surviving Disaster made by the BBC, and the episode "Rescued From Mount St. Helens" from the 2017 series ''We'll Meet Again with Ann Curry'' on PBS. In 2020, Canadian alternative rock band The Tourist Company (from the other Vancouver) released an album called St. Helens. The opening track was titled "Vancouver, Vancouver This Is It ", and was inspired by Johnston's last words. == Works ==